Flue-cutter.



' H. H. THURNTON.'

Patented Mar. 2, 1909 .MU ..7 /lfl NW J i @N HENRY H. THORNTON, OF SOMERVILLE, MASSACHUSETTS.

FLUE-CUTTER.

Specification of Letters Patent.

Patented March 2, 1909.

Application led September 18, 1908. Serial No. 453,613.

'To all whom t may concern:

Be it known that I, HENRY H. THORNTGN, a citizen of the United States, residing at Somerville, county of Middlesex, and State of Massachusetts, have invented an Imrovement in Flue-Cutters, of which the folowing description, in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

This invention relates to fiue cutters which are adapted to cut off a fiue or pipe from the inside.

Elue cutters are usually made with a head with which a feed screw has screw-threaded engagement, and with cutters which are retained in position by a casing and are forced outwardly by advancing the feed screw through the head. In some types of flue cutters the necessary rotary movement is given to the cutters by rotating the head, said head being secured to the casing so that the rotation of the head is communicated to the casing. In other types of flue cutters the rotary movement is imparted to the cutters through the feed screw and the necessary advancing movement of the feed screw is secured by holding the head stationary. In this form of flue cutter the casing has a swiveled engagement with the head.

My invention relates to this latter type of flue cutters, and the object of the invention is to improve iiue cutters of this ty e by simplifying the construction and re ucing the cost of manufacture thereof, and also by providing a construction which will permit the same flue cutter to be used for cutting a large number of different sizes of flues.

My invention also has for its object to improve generally flue cutters of this class all as will be more fully 1hereinafter described and then pointed out in the claims.

Referring to the drawings wherein I have illustrated the preferred embodiment of my invention, Figure 1 is a longitudinal section through a flue cutter embodying my invention; Fig. 2 is an enlarged section on the line a-a, Fig. 1; Fig. 3 is a section on the line b-b, Fig. 1; Fig. 4 is a detail of the gage; Fig. 5 shows the casing which is used for cutting the larger sized flues; Fig. 6 is a view of the fork used to hold the head stationary while the flue cutter is in operation.

The cutters 3 of any suitable or usual construction are revolubly sustained in cutter carriers 4, which carriers are received in openings 5 formed in the side of the casing 6. The cutter carriers are moved laterally by 'the wedge-shaped portion 7 of the feed screw 8, said wedge-shaped portion having the dove-tailed grooves 9 formed therein to receive the dove-tailed ribs 10 on the cutter carriers. The feed screw extends through and has screw-threaded engagement with a head 70, and I prefer to make the head of the shape shown with the long hub portion 11 because this hub portion not only furnishes a long screw-threaded engagement between the head and the feed screw but also constitutes a handle by which the flue cutter may be readily held. The casing 6 is swiveled to the head, and for this purpose I have shown said casing as provided at its end with the flange 12 which fits in a recess 13 formed in the head, said flange being held in place by the cap 14 which is removably secured to the casing by suitable screws 15.

Suitable ball bearings 16 are inserted between the cap and the iange. The interior of the casing 6 is cylindrical, and the wedgeshaped portion 7 of the feed screw is provided with the curved sides 40 which fit the interior of the casing. In this way a firm bearing is afforded between the feed screw and the casing throughout the wedge portion of the former. The dove-tailed grooves 9 terminate at 42, and beyond said point 42 the feed screw is slabbed off on opposite sides at 43 so that when the feed screw has been advanced sufficiently to bring the slabbedoff portions 43 into alinement with the cutter carriers, said carriers can be readily removed from the casing.

17 designates gage fingers which are adapted to rest against the fiue sheet when the end of the casing is inserted in the flue to be cut and which determine the point where the flue is to be cut. These gage fingers are preferably concaved at their ends, as at 18, so that the corners 19 thereof will rest against the iiue sheet. Since there are two such gage 'fingers there are four points 19 to rest against the flue sheet and a much firmer bearing is thus provided than if the gage fingers had squared ends. The gage fingers are carried by a collar 20 which is loosely mounted on the casing. It is necessary to provide some means of adjusting the gage fingers and in order to secure a fine adjustment I form said gage fingers integral with a ring 21 which is screw-threaded onto the collar 20, as shown, so that by turning the ring 21 on the collar 2O through a partial revolution a fine adjustment of the gage fingers can be effected. The ring 21 is locked in its ad justed position by means of a set screw 23 which is screw-threaded through said ring and is adapted to engage in any one of a plurality of grooves 24 formed in the collar 20. In operating this flue cutter the feed screw 8 is withdrawn, as shown in Fig. 1 of the drawings, and the end of the casing is then inserted in the end of the flue to be cut until the fingers 17 engage the flue sheet. The feed screw is then rotated by any suitable means and the head is held stationary. Because of the dove-tailed engagement between the cutter carriers and the wedge portion 7 of the feed screw, the rotation of the feed screw will turn the casing and the cutter carriers within the flue and because the head 70 is held stationary, such rotary movement will advance the feed screw and thus force the cutters outwardly thereby cutting off the end of the flue. For holding the head 70 stationary while the feed screw 8 is rotated, said head is provided with the laterally-extending fork 25 between the branches of which a rod, bar or stick 26 may be inserted, said rod, bar or stick being extended into one of the flues adjacent to that being cut. I propose to employ a reversible motor for operating the feed screw 8 and the advantage of using the fork 25 is that said fork will .hold the head stationary during the rotation of the feed screw 8 in either direction, and thus the operator does not have to pay any attention to holding the head from rotation and can, therefore, devote his energies to the operation of the motor and the placing ofthe instrument properly in the tube or flue to be cut. This fork 25 is preferably provided with a screw-threaded shank 27 which is screw-threaded into the head 70 so that when the device is not being used and is to be packed away, said forli can be removed from the head. It will be noted that the feed screw has a continuous screw-threaded engagement with the head and that the screwthreaded bearing between the feed screw and the head is comparatively long.V rIhe advantage of this construction is that the feed screw is held firmly in its proper position and that-there is comparatively little chance for wear to occur. Furthermore, the hub 11 constitutes a very convenient handle by which the flue cutter may be held in position. Flue cutters as ordinarily made are capable of cutting only two or three sizes of flues, and with most styles of flue cutters it becomes necessary to use two or three different sizes of flue cutters in order that lines of a variety of sizes may be cut. In my invention, however, I have provided for changing the flue cutter over into one adapted to cut larger flues by merely removing one casing and substituting another therefor'. As will be seen from the drawings the inner end of the casing is screw-threaded into a holder portion 30 which is in the form of a sleeve and which has formed therein the flange 12 above referred to, so that said casing can be readily removed from the holder portion. The casing shown in Fig. 1 is one of a plurality of interchangeable casings and is made of a size to fit the smaller sizes of llues. For cutting thc larger sizes of flues I employ another one of the plurality of interchangeable casings which may be constructed as shown in Fig. 5, it being similar to that shown in Fig. l except that it is formed `with the collar or enlargement 33 at the point where the cutter carriers 4 play through the side of the casing, said enlargement being of substantially the same diameter as the interior of the tube or flue to be cut. In order to steady each of the casings 'which are provided with the enlargement 33, I will preferably place at the end of each casing a collar 34 which is also of substantially the same diameter as the interior of the flue. The collar 34 is prefer'- ably removably sustained by the casing and this may conveniently be done by providing the end of the casing with the screw-threaded portion 35 onto which the collar is screwed. In order that the device may work accurately, it is desirable that the collar 34 should be of a diameter to accurately fit the interior of the flue. Assuming that the casing as shown in Fig. 1 is tvvo inches in diameter, then said casing rrfill be adapted for cutting tvo-inch flues. I Afind that the same casing can be readily used for cutting two and a half inch flues if a collar of two and a half inches extcrnal diameter is placed on the threaded end 35 of the casing. For cutting three inch flucs, however, it is desirable to remove the casing shown in Fig. 1 and substitute one of the interchangeable casings having the enlarged'portion 33 as shown in Fig. 5, said interchangeable casing, of course, having a three inch collar 34 on the end thereof. By placing a three and a half inch collar 34 on the end of said casing, it can be readily used for cutting three anda half inch flues, but four inch flues can best be cut by substituting still another interchangeable casing having an enlargement 33 of greater diameter and also having a larger collar 34. f

If the screw-threads 35 on the casing 6 for the smallest sizes of flues come flush with the exterior surface of the casing, said. screwthreads are very likely to become worn when the casing is operating in the two-inch flues. Accordingly I propose to place the screwthreads 35 on a portion of the casing of reA duced diameter, as shown in Fig. 1, so that said screw-threads cannot by any possibility have contact vJith the interior of the flue. It `will be understood, of course, that the out"Y ter carriers which are used with the interchangeable casings havingrthev enlargements 33 must of necessity be larger than those shown in Fig. 1. All of the casings of the set of interchangeable casings have the same interior diameter', and therefore they all fit and coperate with the tapered portion 7 of the feed screw. The enlargement or collar 33 may be formed on the casing in any suitable way, but will preferably be integral therewith.

1 propose to employ a gage of larger diameter than that shown in Fig. l for the casings having the enlargements thereon. This can be readily done by making a gage with the gage 'fingers 17 oilset slightly, as shown at 37 in Fig. 5. Since the gage 'lingers are integral w ith the ring 2l, it will be seen that any gage with its ring can be readily unscrewed from the collar 20, and another gage with the offset 'lingers thereon applied to the collar.

From the above it will be seen that by merely substituting one casing for another the same implement can be used for cutting any size of flue. This is a. decided advantage because it obviates the necessity of buying three or four separate complete flue cutters of difl'erent sizes in order to have on hand a flue cutter adapted to cut any size of i'lue.

1 have not attempted to show herein all embodiments of my invention, but have selected the preferred embodiment for the saire of illustrating the principle of the invention.

Having described my invention, what 1 claim as new and desire to secure by Letters Patent is 1. 'ln a flue cutter, the combination with a head having a recess in one end and provided with an extended hub, of a holder swiveled in said recess, an interchangeable tubular casing detachably secured to the holder' and capable oi' being removed therefrom without taking the holder from the recess, said casing having cutter-receiving apertures, a combined cutter-rotating and cutter-feeding member of substantially uniform diameter, one end of which has permanent screw-threaded engagement with said head and the other end of which is provided. with converging dovetailed grooves, and cutter carriers received within said apertures of the casing and retained in said grooves, whereby said casing may be changed for another casing adapted to cut a different sizeof flue.

2. 1n a ilue cutter, the combination with a head having an extended hub, of an interchangeable tubular casing swiveled to the head but detachable therefrom, said casing having cutter-receiving apertures, a combined cutter-rotating and cutter-feeding member screw-threaded to the head and eX- tending into the casing, one end of which has permanent screw-threaded engagement with the head and the other end of which is coniined within the casing and is provided with two converging dove-tailed grooves, and cutter carriers received in apertures in the casing and retained in said grooves, said member being slabbed ofi on opposite sides at i3 in line with the grooves and at a point which is alined with the cutter carriers when said member is in its 'forward position whereby the cutter carriers can be removed from the casing without removing the member from the head.

3. 1n a flue cutter, the combination with a head. having a recess in one end and provided with an extended hub, of a tubular casing provided with cutter-receiving apertures and having associated therewith a flange which is received within the recess, means to retain said flange in the recess while allowing the casing to turn relative to the head, a combined cutter-rotating and cutter-feeding member of substantially uniform diameter throughout its length, said member having screw-threzuled engagement with the head and also having a wedge-shaped portion located within the casing, cutter carriers mounted in the apertures in the casing and engaging the wedge-shaped portion of said member, a collar loosely mounted on the casing, means to limit the longitudinal movement of said collar and a ring screw-threaded on the collar, said ring having integral therewith lingers.

Li. ln a iiue cutter, the combination with a head having a recess in one end, of a holder swiveled in said recess, an interchangeable tubular casinOl detachably secured to the holder and provided with cutter-receiving apertures, cutter carriers received within said apertures, a combined cutter-rotating and cutter-feeding member of substantially uniform diameter having permanent screwthreaded engagement with said head andprovided with a wedge-shaped portion having engagement with the cutter carriers, and a 'forli extending laterally from the head and adapted to straddle a retaining device inserted in the flue adjacent the part in which the device is operating, whereby said casing may be changed for one of a different size adapted to cut a ilue of a different size.

1n testimony whereof, 1- have signed my name to' this specification, in the presence of two subscribing witnesses.

HENRY 141. THORNTON.

fitnesses:

Louis C. SMITH, THOMAS J. DRUMMOND. 

